1. Field of the Invention
The invention relates to the mechanical and/or chemical processing of substances.
2. Description of the Prior Art
When the particle size of a substance is mechanically reduced, sparks may be generated. This poses the threat of an explosion if the substance is combustible. The chance of an explosion increases with decreasing particle size because small particles ignite more readily than large ones.
In order to reduce the possibility of an explosion, U.S. Pat. Nos. 3,477,650; 3,602,164; and 3,610,594 propose to reduce particle size in an air atmosphere which is deficient in oxygen. To this end, air and fuel are combusted in a furnace to reduce the oxygen content of the air which then forms the atmosphere for particle reduction.
The method of the above patents requires a special furnace which increases the cost of the system used for the method.